Avoid valgrind errors

Avoid valgrind errors

In event handlers, we might destroy other events that are pending in the lists.
We can only run one event safely per select call.

Yes, I've seen these valgrind errors :-)

Jeremy, with ccdd921e61 you had checked in the change to run multiple events.
Do you remember why it was necessary and could not be solved in a different
way?

Volker